[wpimath] Add structured data support for DifferentialDriveWheelPositions (#6412)

wpimath/src/test/native/cpp/kinematics/struct/DifferentialDriveWheelPositionsStructTest.cpp

@@ -0,0 +1,27 @@
+// Copyright (c) FIRST and other WPILib contributors.
+// Open Source Software; you can modify and/or share it under the terms of
+// the WPILib BSD license file in the root directory of this project.
+
+#include <gtest/gtest.h>
+
+#include "frc/kinematics/DifferentialDriveWheelPositions.h"
+
+using namespace frc;
+
+namespace {
+
+using StructType = wpi::Struct<frc::DifferentialDriveWheelPositions>;
+const DifferentialDriveWheelPositions kExpectedData{
+    DifferentialDriveWheelPositions{1.74_m, 35.04_m}};
+}  // namespace
+
+TEST(DifferentialDriveWheelPositionsStructTest, Roundtrip) {
+  uint8_t buffer[StructType::GetSize()];
+  std::memset(buffer, 0, StructType::GetSize());
+  StructType::Pack(buffer, kExpectedData);
+
+  DifferentialDriveWheelPositions unpacked_data = StructType::Unpack(buffer);
+
+  EXPECT_EQ(kExpectedData.left.value(), unpacked_data.left.value());
+  EXPECT_EQ(kExpectedData.right.value(), unpacked_data.right.value());
+}